/// <summary>
        /// Assigns a new server driver to the connection object
        /// </summary>
        /// <param name="groupName">Group name</param>
        /// <param name="master">True if the server connection to assign must be a master</param>
        /// <param name="connection">MySqlConnection object where the new driver will be assigned</param>
        internal static void GetNewConnection(string groupName, bool master, MySqlConnection connection)
        {
            do
            {
                lock (thisLock)
                {
                    if (!IsReplicationGroup(groupName))
                    {
                        return;
                    }

                    ReplicationServerGroup group  = GetGroup(groupName);
                    ReplicationServer      server = group.GetServer(master, connection.Settings);

                    if (server == null)
                    {
                        throw new MySqlException(Properties.Resources.Replication_NoAvailableServer);
                    }

                    try
                    {
                        bool isNewServer = false;
                        if (connection.driver == null || !connection.driver.IsOpen)
                        {
                            isNewServer = true;
                        }
                        else
                        {
                            MySqlConnectionStringBuilder msb = new MySqlConnectionStringBuilder(server.ConnectionString);
                            if (!msb.Equals(connection.driver.Settings))
                            {
                                isNewServer = true;
                            }
                        }
                        if (isNewServer)
                        {
                            Driver driver = Driver.Create(new MySqlConnectionStringBuilder(server.ConnectionString));
                            connection.driver = driver;
                        }
                        return;
                    }
                    catch (MySqlException ex)
                    {
                        connection.driver  = null;
                        server.IsAvailable = false;
                        MySqlTrace.LogError(ex.Number, ex.ToString());
                        if (ex.Number == 1042)
                        {
                            // retry to open a failed connection and update its status
                            group.HandleFailover(server, ex);
                        }
                        else
                        {
                            throw;
                        }
                    }
                }
            } while (true);
        }
        /// <summary>
        /// Adds a Server Group to the list
        /// </summary>
        /// <param name="name">Group name</param>
        /// <param name="groupType">ServerGroup type reference</param>
        /// <param name="retryTime">Time between reconnections for failed servers</param>
        /// <returns>Server Group added</returns>
        internal static ReplicationServerGroup AddGroup(string name, string groupType, int retryTime)
        {
            if (string.IsNullOrEmpty(groupType))
            {
                groupType = "Pomelo.Data.MySql.Replication.ReplicationRoundRobinServerGroup";
            }
            Type t = Type.GetType(groupType);
            ReplicationServerGroup g = (ReplicationServerGroup)Activator.CreateInstance(t, name, retryTime) as ReplicationServerGroup;

            groups.Add(g);
            return(g);
        }
        /// <summary>
        /// Gets a Server Group by name
        /// </summary>
        /// <param name="groupName">Group name</param>
        /// <returns>Server Group if found, otherwise throws an MySqlException</returns>
        internal static ReplicationServerGroup GetGroup(string groupName)
        {
            ReplicationServerGroup group = null;

            foreach (ReplicationServerGroup g in groups)
            {
                if (String.Compare(g.Name, groupName, StringComparison.OrdinalIgnoreCase) != 0)
                {
                    continue;
                }
                group = g;
                break;
            }
            if (group == null)
            {
                throw new MySqlException(String.Format(Resources.ReplicationGroupNotFound, groupName));
            }
            return(group);
        }
        //private static Dictionary<string, ReplicationServerSelector> selectors = new Dictionary<string, ReplicationServerSelector>();

        static ReplicationManager()
        {
            Groups = groups;

            // load up our selectors
            if (MySqlConfiguration.Settings == null)
            {
                return;
            }

            foreach (var group in MySqlConfiguration.Settings.Replication.ServerGroups)
            {
                ReplicationServerGroup g = AddGroup(group.Name, group.GroupType, group.RetryTime);
                foreach (var server in group.Servers)
                {
                    g.AddServer(server.Name, server.IsMaster, server.ConnectionString);
                }
            }
        }
        /// <summary>
        /// Gets the next server from a replication group
        /// </summary>
        /// <param name="groupName">Group name</param>
        /// <param name="isMaster">True if the server to return must be a master</param>
        /// <returns>Replication Server defined by the Load Balancing plugin</returns>
        internal static ReplicationServer GetServer(string groupName, bool isMaster)
        {
            ReplicationServerGroup group = GetGroup(groupName);

            return(group.GetServer(isMaster));
        }